1. Field of the Invention
The present invention relates to a shorting contact support for ignition receptacles, and more particularly to contact supports as used in airbag restraining systems for motor vehicles.
2. Description of the Prior Art
The igniter and the electrical supply lines for such airbag restraining systems can be accommodated on the front in the hub cushion of the steering wheel. In this case, the electrical connection between the igniter and the control system is a very sensitive point in the restraining system, since any uncontrolled fluctuations in potential which arise on the igniter""s contact pins can result in the airbag being triggered unintentionally.
For this reason, known plug connector systems have a shorting bridge in the igniter""s ignition receptacle and between the igniter""s contact pins, said shorting bridge being released from these contact pins on insertion of the plug""s plug-in projection if electrical contact has already been made between the plug sockets and contact pins. During the insertion procedure, such a shorting bridge effectively prevents the igniter from being unintentionally triggered by electrostatic energy which may have accumulated in the region of the igniter.
The document EP 0 591 947 describes a plug connector having such a shorting bridge, which has been designed such that the shorting bridge is arranged in a shorting contact support.
A particular disadvantage of such shorting contact supports is that, once the plug-in projection has been inserted into the holder in the shorting contact support, the shorting bridge is lifted from the igniter""s contact pins without providing any further protection against electromagnetic interference or electrostatic charges between the contact pin and contact eye connection. One occurrence during the insertion procedure may be that the shorting contact support or the ignition receptacle with its contact pins is at a different potential from that of the plug-in projection with its contact sleeves. A further disadvantage in this case is that this potential difference can be compensated for only by screening on the contact pins and contact sleeves, or else the electrical energy is dissipated by means of the control electronics connected to the contact sleeves of the contact plug. In this case, an insertion procedure may damage the control electronics.
The document DE 198 51 301 discloses an electrical plug connector for igniters which comprises a housing and a plug-in projection which is integrally formed on the housing and has, along the insertion direction of the plug connector, contact elements for engaging with corresponding mating pieces in a connector part, and at least one guide element for engaging in a complementary part, the screening device having an electrically conductive earthed ring which is arranged around the contact elements, and contact tongues for dissipating electrical charge in the connector part. A particular disadvantage of this plug connector is that it provides no possibility for shorting the igniter""s contact pins. Furthermore, this plug connector is suitable only for xe2x80x9cintelligentxe2x80x9d igniters, which means that the igniters have dedicated control electronics.
The object of the present invention is to present a shorting contact support which is suitable both for intelligent and non-intelligent igniters. In addition, the aim is to improve the protection of the electrical connection between the contact pins in the igniter receptacle and the contact sleeves on the plug against electrostatic charge and electromagnetic interference.
The object is achieved by the features of the present invention.
The inventive shorting contact support for igniter receptacles comprises a shorting bridge having at least two resilient contact elements for electrically connecting contact pins on an igniter, the shorting bridge also having at least one first plate. In addition, the shorting contact support comprises a support housing having an annular base in which two diametrically opposite wings are integrally formed parallel to the insertion direction, so that a plug-in projection can be inserted between said wings. In this arrangement, the shorting bridge has a second metal plate, the two metal plates being essentially parallel opposite one another and being connected to one another by means of at least one ring segment. Furthermore, at least one of the plates has at least one contact tongue so that it is electrically connected to a screening or earth connection situated on the plug when the plug is inserted into the ignition receptacle.
In the case of such a shorting contact support, a particularly advantageous feature is that, when the plug-in projection is inserted into the shorting contact support, the shorting bridge can be pulled to earth with the contact pins on the igniter, that is to say they are at a defined potential and any electrostatic charges can flow away via this earth.
One advantageous refinement of the invention is that the lateral edges of the metal plates form cutting contacts which, in the assembled state, project laterally from the wings. What is special about this is that, when the shorting contact bridge is inserted into the metallized igniter receptacle, the latter is automatically earthed as well, this metallization operating as a Faraday cage.